To Import Pipe Network Data From a Storm Sewers .stm File
Click Insert tabImport panelStorm SewersFind.
In the Import Storm Sewers File dialog box, navigate to the desired .stm file, select it, and then click Open.
You are prompted to either update the existing pipe network, or to create a new pipe network.
Choose to either update the existing pipe network, or to create a new pipe network.
Note: It is important to note that rules are not applied to pipes or structures when importing pipe networks from either LandXML or from the Storm Sewers Extension.